洞庭湖区社鼠的繁殖生态

在洞庭湖区域,社鼠（Niviventer confucianus）种群主要栖息在山区和丘陵地带的林地内.总体而言,其种群雌性比基本维持在50%左右,但在季节间和年龄组间有一定的差别,雌性比在冬、春季较低,夏、秋季的雌性比都超过50%.年龄组间,雌性比最高的为幼年组66.7%,亚成年和成年组的雌性比接近50%,而老年组的雌性比为最低,为33.3%.所有雌鼠全年的怀孕率为31.1%,平均胎仔数为3.7只,繁殖指数为0.58.春、夏季怀孕率较高,冬季没有捕获到怀孕的雌鼠,仅捕获到有怀孕经历（有宫斑）的雌鼠.繁殖指数在夏、秋季维持高峰水平.雌性社鼠总的参产率为53.3%,各季间呈现从春、夏到秋逐渐增加的趋势,冬季停止怀孕.可见夏、秋季为雌鼠的繁殖高峰期.随着年龄组增长,平均胎仔数有明显增加的趋势,老年组胎仔数最高,而繁殖指数以成年组最高,说明成年组是种群中繁殖的主体.雄性社鼠的睾丸下位率全年总计为75.6%,分四季平均为86.0%,夏、秋季维持在较高水平,冬、春季稍低,低谷在春季.下位睾丸的重量与大小有明显的季节变化,呈现春、夏、秋、冬逐渐下降的规律,春季与冬季相比,有显著性差异,说明开春后,雄性社鼠在生殖潜能上已有明显变化.这些特征与雌鼠的繁殖高峰基本吻合.说明社鼠主要在春、夏、秋季繁殖,繁殖盛期在夏秋季.从不同年龄组看,幼年组个体不参与繁殖,亚成年组个体开始参与繁殖,繁殖主体是成年组个体.     

棕色田鼠种群繁殖特征及密度制约调节(英)

1992年～1994年在河南灵宝市郊黄土高源农作区春夏秋逐月捕获并解剖棕色田鼠1757只（雌性961只,雄性796只）,总性比为1．2073。全年都有繁殖鼠出现,但怀孕率、胎仔数、性比、繁殖指数有明显的季节变化,年间也有一定的差异。不同年龄组的性比、怀孕率、胎仔数、繁殖指数、睾丸下降率不同。种群密度对繁殖特征有明显的调节作用。高密度年份的棕色田鼠的性比、怀孕率和繁殖指数低于低密度年份。高密度区种群的繁殖强度受到抑制,雌鼠怀孕率、睾丸下降率低于低密度种群。     

川西平原大足鼠的种群生态学 III.繁殖

在川西平原利用标志重捕、夹捕解剖和半自然条件下笼养的方法,提供了1989～1995年大足鼠种群雄性和雌性个体处于繁殖状态的比例、胎次数、每胎幼仔数、幼年个体的补充和发育等有关繁殖的基本资料。结果显示,大足鼠极灵活的繁殖策略 提高了这个物种幼年个体的存活,使该物种在可预见而频繁的周期性变化的农田环 境中能够保持相对稳定的种群。大足鼠的繁殖特征主要有：处于繁殖状态的雄性比例较大（平均0.491,95%置信区间0.451和0.534）,怀孕雌性的比例较小（平均0.227,95％置信区间0.213和0.301）,较高和相对稳定的繁殖能力（每年4胎,每胎8.245±0.452只）,雌性幼仔较慢的生长和性成熟（4月）,以及幼年个体加入种群与春季的小麦和秋季的水稻成熟相同步。这些繁殖特征使得大足鼠的繁殖活动集中在有利的时间。结果,虽然伴随繁殖活动雌雄性的个体质量下降,但仍能在短暂的时间里恢复到原来的水平。将大足鼠的胎仔数与一些关于中国啮齿动物繁殖参数地理变异 的研究进行了分析比较,发现后者提供的资料尚不足以支持中国所有啮齿动物都有 "胎仔数随纬度增加"的过分简单的一般结论。每一个物种种群都有自己的最优胎 仔数,但最优胎仔数不一定随纬度而增加。我们认为在大尺度上研究如胎仔数这样的生活史性状时,生活史多样性的提法比单一性状的过分简单的一般化更好。     

鄱阳湖区黄毛鼠(Rattus losea)繁殖生态

2015—2016年对鄱阳湖区的滨湖农田和湖滩草洲的黄毛鼠种群繁殖进行了研究。研究结果表明,其种群雌雄比为81.36%,在不同的季节、生境和年龄组之间都有一定的差别,雌雄比在夏季较低,春、秋、冬季的雌雄比都超过了50.00%,其中冬季的达到了133.33%。农田和湖滩草洲上的雌雄比也都超过了50.00%,且农田的高于湖滩草洲的。在不同的年龄组之间,雌雄比最高的为幼体组140.00%,其次为成体90.20%。所有雌鼠全年的怀孕率为45.26%,平均胎仔数为6.74只,繁殖指数为1.36。夏和秋季的怀孕率都较高,冬季未捕获到怀孕鼠,仅捕获到有怀孕经历(有宫斑)的雌鼠。从繁殖指数看,春、秋季维持高峰水平,且秋峰高于春峰。雌性黄毛鼠总的参产率为71.58%,各季节间变化呈现单峰曲线,夏季最高,其次是秋季和春季,冬季停止怀孕。随着年龄的增长,平均胎仔数有明显增加的趋势,成体组胎仔数最高,而繁殖指数也是以成体组最高,说明成体组是种群中繁殖的主体。雄性黄毛鼠的睾丸下降率全年总计为81.36%,分四季平均为79.64%,春、夏、秋季都维持在较高水平,冬季最低。下位睾丸的大小季节性差异极显著(P0.01),春季与冬季相比,有显著性差异,说明开春后,雄性黄毛鼠在生殖潜能上已有明显变化。这些特征与雌鼠的繁殖高峰基本吻合。说明黄毛鼠主要在春、夏、秋季繁殖,繁殖盛期在春、秋季。从不同的年龄组看,幼体组个体不参与繁殖,亚成体组个体开始参与繁殖,繁殖主体是成体组个体。     

黑线姬鼠(Apodemus agrarius)的种群繁殖参数及其地理分异特征

黑线姬鼠（Apodemus agrarius）是我国广大地区的主要害鼠之一,是余庆县农田害鼠优势种,占总鼠数的94.81%。探讨其种群繁殖参数的变动规律及其地理分异特征,对其种群数量预测预报具有重要意义。通过对1987-2005年贵州省余庆县黑线姬鼠种群繁殖参数分析结果表明：研究期间共解剖标本5497只,其中,雌鼠2698只,雄鼠2799只,黑线姬鼠在当地1-11月份均可繁殖,主要繁殖期在3-10月份,每年4-5月份和8-9月份出现2次妊娠高峰。种群总性比（♀/♂）为0.96,多年平均怀孕率为36.91%±6.79%,平均胎仔数为5.33±1.07只,平均繁殖指数为0.81±0.17,平均睾丸下降率为59.13%±7.89%。不同年龄组种群繁殖力存在显著差异,随着种群年龄的增长繁殖力不断增加,成年Ⅰ组、成年Ⅱ组、老年组是种群繁殖的主体。种群繁殖参数不同年度之间比较稳定,不同月份、不同季节之间变化差异较大,具有明显的季节变化特征。年均种群密度与年均繁殖指数呈极显著正相关,与胎仔数显著正相关,与年均怀孕率、睾丸下降率、性比相关性不显著,繁殖指数是影响黑线姬鼠种群密度的重要因子。比较全国各地黑线姬鼠种群繁殖参数的地理分异特征认为,黑线姬鼠种群繁殖参数具有明显的地理分异现象,胎仔数、生殖强度由南向北逐渐增加,具有随纬度的升高趋向增加的特征;在高纬度地区繁殖时间较短;性比与纬度、经度的变化关系密切;各繁殖参数与海拔的变化相关性不明显,可排除海拔因素的影响。     

中国啮齿类繁殖参数的地理变异

本文综述了我国8个鼠种(Cricetulus triton,Cricetulus barabensis,Microtus fortis,Apo—demus agrarius,Rattus norvegicus,Rattus losea,Rattus flavipectus,Mus musculus)的繁殖参数在不同纬度、经度和海拔上的变异趋势。8种鼠的胎仔数,怀胎率和生殖强度(胎仔数×怀胎率/性比)随纬度、海拔增加有增加的趋势;繁殖期和性比()有减小趋势。各繁殖参数在经度上的变化规律尚不清楚。野外小家鼠的胎仔数,雌性比例、怀胎率和生殖强度均比居民区大。 在高纬度、高海拔地区,种群增大生殖强度在于补偿较短的繁殖期和较低的存活率,以维持种群稳定和繁衍成功。这种繁殖对策是自然选择的结果。     

洞庭湖区东方田鼠繁殖特性研究

１９９２年１月～１９９４年１２月,作者在东洞庭湖区岳阳县麻塘区调查,３年捕获并剖检东方田鼠１３９２只,其中雌鼠５９９只,雌性比♀／（♂＋♀）＝４３．０％。该鼠全年繁殖,盛夏５～７月怀孕率较低,冬季１２～２月怀孕率比同域其它鼠种显著偏高。３年合计总怀孕率为２９．２％．平均胎仔数（ｘ±ＳＥ）为５．１３±０．１２只,平均窝仔数４．６０±０．２７只,雌鼠和雄鼠的繁殖强度随年龄增长而递增。室内饲养的东方田鼠妊娠期约２０天,窝仔数４．３３±０．３３只,雌鼠５０～６０天成熟,雄鼠稍迟。枯水期（１１月～翌年４月）东方田鼠主要栖息于湖洲草地,汛期（５～１０月）主要栖息于过垸内稻田。在不同栖息地其繁殖力差别较大,湖洲的繁殖强度最高,稻田区次之,岗地最低,反映它在各栖息地生态适合度不同。文中还对全国４个亚种的繁殖参数作了比较。     

洞庭平原黑线姬鼠繁殖特性研究

１９８６年１０月－１９９０年１０月在湖南省桃源县和汉寿县的稻作区逐月调查,夹捕黑线姬鼠长江亚种２７６８只,雌性占４５。６％。主要繁殖期３－１１月,研究期内的月平均怀孕率为４８．６±４．０％、平均胎仔数为５．３±０．２只。繁殖指数为２．３６±０．２９。以上３个参数及种群性性比有季节性变化,４－５月和７－１０月为２个妊娠高峰;雄性睾丸下位率和雌性怀孕率有同步变动的趋势。５年龄组之间,其性比、怀孕率和繁     

捕杀对高原鼢鼠种群年龄结构及繁殖的影响

捕杀高原鼢鼠后,残鼠种群与自然种群年龄结构相比较,５月差异性显著（Ｘ２＝９９７,Ｐ＜００５）;７月和１０月差异极显著（Ｘ２＝１５１３４,Ｘ２＝１５６１２,Ｐ＜００１）。５月,残鼠种群成年Ⅰ组占最大比例（５３４５％）;自然种群成年Ⅱ组占最大比例（４８４４％）。７月,残鼠种群幼年组和亚成年组所占比例之和（３５０６％）明显高于自然种群（２２００％）（Ｐ＜００５）。１０月,残鼠种群近老年组和老年组所占比例之和（９６２％）明显低于自然种群（２３０８％）（Ｐ＜００５）。残鼠种群成年Ⅰ组雌鼠怀孕率（８４６２％）明显高于自然种群（５８３３％）（Ｐ＜００５）;平均胎仔数（３３２）也高于自然种群（２８５）,但差异不显著（Ｐ＞００５）。     

捕食干扰对Myospalax baileyi种群繁殖力的影响

采用去除法对高原鼢鼠种群繁殖力的变化进行了研究。结果表明,在未受干扰的种群内有５０％的雌性成本不参与繁殖,其平均胎仔数３．４只,种群受干扰后其成体鼠的比例下降,幼体鼠的比例相对提高,繁殖鼠的比例和平均胎仔数均相应增加,随着干扰程度的加剧,其繁殖力也明显增加。土壤硬度和杂类草生物量决定了高原鼢鼠的种群密度,而种群密度是影响繁殖力的主要因素,未受捕食干扰的种群其数量接近于环境容纳量,由于密度作用使其繁     

Variation of reproductive traits in a population of the lizard Lacerta vivipara

Variation in reproductive traits (sexual maturity, clutch size, clutch weight, mean egg mass, newborn weight) was studied during a four year period in a population of the live-bearing lizard Lacerta vivipara . Sexual maturity was associated with attaining a minimum body size. Clutch size increased with female body length and litter weight increased with clutch size. A major component of the within year variation in these reproductive traits was attributable to female size. Analysis of successive clutches in individual females indicated that a significant fraction of the variation in litter size, adjusted for female length, was due to consistent differences between individuals. Newborn weight varied within and among litters, but no relations between hatchling mass or mean egg mass in a litter and other traits were detected.
Size-adjusted reproductive performances remained constant during the course of this study, even though environmental conditions (weather factors, food availability) varied annually. Observed among year variations in reproductive characteristics were attributable to differences in the body size distributions of the adult females.     

Environmentally related life history variations in Geophagus brasiliensis

The hypothesis of environmentally related life history variations between two Geophagus brasiliensis populations was investigated by comparing riverine and lacustrine populations. Mean standard length and length at maturity were higher in the lagoon population. Higher fecundity and gonado-somatic indices reflected higher reproductive investment in the river population. In the river, reproduction took place throughout the year, whereas in the lagoon spawning was restricted to spring and summer. Both populations presented synchronous oocyte development, indicating total spawning. Nevertheless, the variation in traits suggests that both populations exhibit environmentally related variations in their life history patternss.     

Phenotypic divergence in reproductive traits of a moth population experiencing a phenological shift

Allochrony that is reproductive isolation by time may further lead to divergence of reproductive adaptive traits in response to different environmental pressures over time. A unique “summer” population of the pine processionary moth Thaumetopoea pityocampa, reproductively isolated from the typical winter populations by allochronic differentiation, is here analyzed. This allochronically shifted population reproduces in the spring and develops in the summer, whereas “winter” populations reproduce in the late summer and have winter larval development. Both summer and winter populations coexist in the same pine stands, yet they face different climatic pressures as their active stages are present in different seasons. The occurrence of significant differences between the reproductive traits of the summer population and the typical winter populations (either sympatric or allopatric) is thus hypothesized. Female fecundity, egg size, egg covering, and egg parasitism were analyzed showing that the egg load was lower and that egg size was higher in the summer population than in all the studied winter populations. The scales that cover the egg batches of T. pityocampa differed significantly between populations in shape and color, resulting in a looser and darker covering in the summer population. The single specialist egg parasitoid species of this moth was almost missing in the summer population, and the overall parasitism rates were lower than in the winter population. Results suggest the occurrence of phenotypic differentiation between the summer population and the typical T. pityocampa winter populations for the life‐history traits studied. This work provides an insight into how ecological divergence may follow the process of allochronic reproductive isolation.     

内蒙古阴山北部农牧区长爪沙鼠种群适应特征的比较研究

长爪沙鼠(Meriones unguiculatus)是内蒙古阴山北部地区主要的农牧业害鼠。有关它的生态学及其危害已有过一些报道(夏武平等,1956; 赵肯堂,1960;夏武平等,1966;夏武平等,1982; 秦长育,1984)。对于农作区和草原区种群的适应性差异迄今未见研究。     

长爪沙鼠种群繁殖的季节性特征

长爪沙鼠是分布于我国北方典型和荒漠草原及农牧交错区的优势鼠种之一。2000 年10 月至2004 年10 月通过标志重捕法研究了栖息于内蒙古农牧交错区草地生境的种群动态。对其不同季节出生群性成熟特征和种群性成熟比率、繁殖个体比例、个体月补充率等繁殖参数的季节特征研究显示:冬季和春季出生的个体性成熟较夏季出生的个体快,尤雌鼠表现突出,其3 个季节出生群的性成熟时间分别为4. 6 ± 0.2、4. 4 ± 0.8 和7.7 ± 0.4月龄。种群性成熟比率、繁殖个体比例和个体补充率月间差异显著,季节消长明显,即春季最高,秋季(9 ～10月间)最低。结果还显示,种群性成熟比率与气温和降水负相关。长爪沙鼠喜栖于植被稀疏、低矮的干燥沙质土壤环境。从初春到夏末,随降水和气温增加其栖息生境的植被由低矮稀疏变得高而稠密,土壤湿度和粘性亦随之提高,地面种子库因发芽贮量减少,适宜生境的减少可能加剧了社群竞争,抑制了种群的繁殖表现。长爪沙鼠种群繁殖的季节变化反映了其生活史对策中适应高纬度气候和食物的季节波动的重要特征。     

Reproductive characteristics of free-livingCalomys venustus (Rodentia, Muridae)

Calomys venustus showed a cyclic seasonal pattern of reproductive activity characterized by a period of repose and a variable length of the period of sexual activity between August—September to May—June. The study was done from 1983 to 1999. During this time the population density increased from October—November to the end of autumn and sharply decreased in winter. Three peaks in rate of pregnancy were recognized in the breeding period: spring, summer and late summer. The average litter size was different among the three peaks in rate of pregnancy. The reproductive pattern had a peak at the beginning of the spring produced by overwintering animals, and another peak in summer-autumn caused by the reproductive activity of young born in the same period in which they breed. The spring cohort exhibited the greatest breeding contribution suggesting that this cohort is principally responsible for the yearly peak in abundance.     

Influence of weather and phenotypic characteristics on pregnancy rates of female roe deer in central Italy

In many ungulates, female fecundity is influenced by weather, population density and body condition. Based on a six-year survey of the reproductive tracts of adult female roe deer (Capreolus capreolus) harvested in the province of Pisa (Tuscany, central Italy), we evaluated the influence of weather, population density and individual characteristics on pregnancy rates. Eighty-five percent of females were pregnant, with a median litter size of two (range one—three). We found that pregnancy rate was positively correlated with summer rainfall and body mass of females, whereas early-winter conditions, spring rainfall, the age of females and density-dependent factors did not appear to influence pregnancy rate. These results reflect the particular seasonal variation in the abundance and quality of resources in Mediterranean habitats and show that heavier females (high-quality mothers) are more productive than lighter females.     

Atypical reproductive cycles in a population of Sceloporus grammicus (Squamata: Phrynosomatidae) from the Mexican Plateau

The spiny lizard Sceloporus grammicus (Squamata: Phrynosomatidae) is a small reptile from central México and the southern United States, occurring in a wide geographic area characterized by extensive variation in topographic and climatic regimes. Genetic variation among lineages from central México is substantial, though the extent to which this variation corresponds with life-history traits remains obscure. To address part of this puzzle, we studied a population of S. grammicus from Tepeapulco, Hidalgo, México. Male-biased sexual dimorphism was extensive in this population; males were larger than females overall, and expressed proportionately larger heads and longer limbs. Minimum size at sexual maturity was similar in the sexes (males: 43 mm; females: 42 mm). In contrast to other populations from the Central Plateau, reproductive activity of males and females was synchronous. Testicular recrudescence of adult males was initiated in October-November, and maximum testis size maintained from December to July. Female reproductive activity showed no clear seasonal pattern: females had vitellogenic follicles from October to July, and pregnant females were found throughout the year. Female body size was not related to litter size. Neither male nor female gonadal mass was correlated with any abiotic environmental variable examined. Differences in reproductive characteristics among populations of S. grammicus might be indicative of plasticity in response to local environmental conditions, local adaptation, or complex gene × environment interactions. We consider these results in the context of previously studied populations of S. grammicus from the Central Plateau and elsewhere, and propose directions for future research.     

Decreased sexual signalling reveals reduced viability in small populations of the drumming wolf spider Hygrolycosa rubrofasciata

One of the important goals in conservation biology is to determine reliable indicators of population viability. Sexual traits have been suggested to indicate population extinction risk, because they may be related to viability through condition dependence. Moreover, condition-dependent sexual traits may be more sensitive indicators of population viability than early life-history traits, because deleterious fitness effects of inbreeding tend to be expressed mainly at the end of the species' life history. However, empirical evidence of the significance of sexual behaviour for population viability is missing. In this study, we examined two male sexual traits and survival in 39 different-sized and isolated natural populations of the wolf spider, Hygrolycosa rubrofasciata. We also used several traits to estimate female reproductive success in 25 populations of H. rubrofasciata. According to previous studies, H. rubrofasciata males have a costly and condition-dependent acoustic signal, courtship drumming, which is the target of female choice. Males with a high drumming rate have considerably higher viability than males with a low drumming rate, and females that mate with the more actively drumming males gain genetic benefits in terms of increased offspring viability. Our results show that males in small populations had both lower survival and lower drumming rate than males in larger populations. However, we did not find any evidence for a decline in important early life-history traits (offspring number, hatching success or offspring body mass) or female body mass in small populations. Our results have two important messages for conservation biology. First, they show that sexual traits can be used as sensitive indicators of population viability. Second, the indirect benefits of female choice in terms of good genes might partially compensate for the reduction of viability in declining populations. Also, our results support the view that deleterious effects of small population size are expressed at the end of the species' life history.